The present invention relates to a method for restoration of a cavity of a tooth and, more particularly, a method for restoration of a cavity of a tooth by firmly bonding a tooth and a dental composite resin with a resin reinforced type glass ionomer cement in a dental treatment for restoration of the cavity of the tooth by using the dental composite resin.
Since a dental composite resin obtained by kneading and mixing quartz powder and Bis-GMA, which is a synthesized dimethacrylate monomer was developed by R. L. Bowen in about 1960, the dental composite resin has been improved in a base monomer, filler, polymerization method or the like, and at present is widely used as a dental restorative material in view of a good aesthetic quality, reasonable cost, operational precision and the like. Further, recently, with improvement of a physical property thereof, the dental composite resin has been used as a dental restorative material to be filled into not only a anterior teeth but also a posterior teeth.
The dental composite resin is a composite material obtained by combining a methacryl resin which is an organic polymer and an inorganic and/or an organic filler. With the combination of the methacryl resin and the filler, the dental composite resin has a suitable hardness, bending strength, abrasion resistance, coefficient of thermal expansion, polymerization contraction amount, water absorption amount, or the like for use in a mouth. The dental composite resin is roughly divided into two groups, namely, a chemical polymerization type composite resin and a photo-polymerization type composite resin.
However, the dental composite resin itself does not have a bonding property with respect to a tooth. Therefore, in case the dental composite resin is filled into a cavity of a tooth, it is normally necessary to use a bonding agent to thereby adhere to the tooth. The bonding agent comprises, generally, an adhesive monomer having a hydrophobic group, such as a benzene ring and alkyl group, and a hydrophilic group, such as a phosphoric acid residual group and a carboxyl group, in the same molecule; a monomer for a purpose of a dilution or the like; a polymerization catalyst; and a solvent. The bonding agent is applied, with a sponge or the like, to a bonding surface of a tooth on which a cavity is formed, and a volatile component thereof is evaporated by air to form a thin layer thereon. If necessary, the bonding agent is hardened by chemical polymerization or photo-polymerization, and the composite resin is filled thereon to harden so that the tooth and the composite resin are bonded together.
Further, at present, there has been widely employed a tooth restorative method wherein prior to application of the bonding agent, a tooth surface treating agent containing an aqueous solution of acid as a main component and a primer containing an aqueous solution of a hydrophilic monomer or an ethanol solution as a main component are used to improve a bonding property. The tooth surface treating agent is mainly used for removing a smear layer formed by pushing against a tooth surface, saliva and cutting wastes produced when a tooth is cut or a cavity is formed. The primer is used for adapting the bonding agent to the dentin and sufficiently infiltrating the monomer of the bonding agent into the tooth. Also, the primer plays a role in reforming quality of the dentin by being applied to the dentin surface of a treated tooth and infiltrated thereto, so that the dentin is improved to be a state suitable for being bonded to the composite resin.
Therefore, a conventional tooth restorative method comprises, generally, the following steps: application of a tooth surface treating agent, washing with water and drying, application of a primer, drying, application of a bonding agent, drying and hardening, filling of a composite resin, and hardening.
However, since the conventional tooth restorative method includes many steps and is complicated, restoration of the tooth takes much time. Further, operations are very difficult, and application and drying of the primer and the bonding agent require fine techniques, so that an operational mistake is liable to occur, a big difference may be caused in finishings depending on dentists as technicians, and a stable bonding property can not be obtained. Also, in case there is a defect in bonding between the composite resin and the tooth, even in a part, water or the like penetrates through the part to cause a marginal leakage; bacteria or the like may enter therein to cause dental pulp stimulus or secondary caries, or cause marginal fracture or falling-off of the tooth.
Thus, there has been required an improved tooth restorative method wherein a treating operation can be completed in a simple method and in a short time; the composite resin and the tooth can be firmly bonded together; little difference is observed in finishings depending on technicians; and there is no possibility of pain or dental pulp stimulus after a treatment.
Therefore, it is an object of the present invention to provide a novel tooth restorative method wherein a resin reinforced type glass ionomer cement is used to firmly bond a tooth and a dental composite resin in a dental treatment for restoration of a cavity of a tooth with the dental composite resin.